Rheems is a census-designated place (CDP) in Lancaster County, Pennsylvania, United States situated between the boroughs of Elizabethtown and Mount Joy and is located entirely within West Donegal Township, Pennsylvania. The population was 1,598 during the 2010 census.
According to the United States Census Bureau, the CDP has a total area of 1.2 square miles (3.1 km2), all of it land.
As of the census of 2000, there were 1,557 people, 513 households, and 439 families residing in the CDP. The population density was 1,321.7 people per square mile (509.5/km²). There were 521 housing units at an average density of 442.3/sq mi (170.5/km²). The racial makeup of the CDP was 97.75% White, 0.26% African American, 0.13% Native American, 0.45% Asian, 0.13% Pacific Islander, 0.32% from other races, and 0.96% from two or more races. Hispanic or Latino of any race were 1.09% of the population.
There were 513 households, out of which 42.1% had children under the age of 18 living with them, 78.6% were married couples living together, 5.5% had a female householder with no husband present, and 14.4% were non-families. 10.7% of all households were made up of individuals, and 3.5% had someone living alone who was 65 years of age or older. The average household size was 2.88 and the average family size was 3.10.
In the CDP the population was spread out, with 26.5% under the age of 18, 6.7% from 18 to 24, 33.2% from 25 to 44, 20.9% from 45 to 64, and 12.8% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 94.1 males. For every 100 females age 18 and over, there were 92.8 males.
The median income for a household in the CDP was $55,170, and the median income for a family was $54,643. Males had a median income of $41,047 versus $26,683 for females. The per capita income for the CDP was $19,530. None of the families and 0.6% of the population were living below the poverty line, including no under eighteens and none of those over 64.